High-density, nonmagnetic stainless steel



United States Patent 3,156,558 HIGH-DENSITY, NONMAGNETIC STAINLESS STEEL Samuel J. Rosenberg and Thomas P. Royston, Jr., Wash- I ington, D.C., assignors to the United States of America as represented by the Secretary of Commerce N0 Drawing. Filed Oct. 3, 1961, Ser. No. 142,740 4 Claims. (Cl. 75128) This invention relates to a high density, nonmagnetic 3,156,558 Patented Nov. 10, 1964 out in air in a 16 pound laboratory induction furnace and the metal was poured into the form of 1 /2 inch diameter bars. These were given a four-hour homogenizing anneal in vacuum at 2000 F. prior to hot working. The steels were hot worked by forging and swaging to rods of about 0.6 inch diameter. Hot working was carried out in the temperature range of about 2100 to 1600 F.

After hot working, the rods were cut into lengths of about 6 inches and turned between centers for cleaning.

10 Samples of the clean, hot-worked material were then stainless steel. taken for spectrochemical and chemical analyses and for By long established custom, the values of weights have determination of density and magnetic permeability. The been expressed as weight in air against standards having analyses of the two steels that closely approached the dea density of 8.4 grams per cubic centimeter. Weights sired density are shown in the following table:

Table II National Percent Bureau of Standards Mark Carbon Manga- Silicon Chro- Nickel Tung- Nitronese mium sten gen Determination of permeability and density gave the following values:

Table III Magnetic Permeability Density, g. per en. cm.

(H=300 Oersteds) National Bureau of Standards Mark As Hot As Annealed As Cold As Hot As Annealed Worked Worked Worked SW-12 1. 00s 1. 019 1. 03 s. 42 s. .4 SW-lB; 1. 000 1. 024 1. 03 s. 45 s. 45

that have this density may be compared without a cor- It is noted that an increase in magnetic permeability rection for air buoyancy being required. was obtained after annealing the hot-worked material.

Brass having a density of 8.4 g. per cu. cm. has been The remanent induction of the hot-worked specimens was used for many years as material for standard weights. It measured after they had been subjected to magnet zing is nonmagnetic, a necessary property for standards of forces of several thousand oersteds. The measured remamass. It is not, however, an ideal material since it nent induction was negligible in comparison with the tarnishes and thus is subject to changes in weight. earths field.

Accordingly, it is an object of the present invention It is understood that while laboratory techniques were to provide a stainless steel that has the required density used in preparing the above alloys, which were given by and is nonmagnetic. Way of example, other conventional furnace procedures This is accomplished by increasing the density of an may be followed in using the present invention. austenitic stainless steel by the addition of tungsten and What is claimed is: maintaining austenite stability by proper balance of chro- 1. A high density, nonmagnetic steel, of approximately mium and nickel. The preferred percent of elements and 8.4 grams/0111. and consisting essentially of: the range or maximum percent ofh elements, besides iron carbon 020% maximum and the usual impurities, used in te preseilt nvention are manganese 200% maximum indicated in the following composition ta e. phosphorous 0 04O% maximum Table I sulfur 0.030% maximum silicon 1.60% maximum 0 chromium 15.5 to 17.5% nickel 31.5 to 33.5% Preferred Range tungsten to 100% Maximum and the balance of said steel being essentially iron.

2. A high density, nonmagnetic steel of approximately g ikgf 9: 3:38 8.4 grams/cm. and consisting essentially of: glllifislphorum 23;: carbon 0.10% Silicon. 1.2 1.60 max. manganese 1.70% 01.1mm gggggg; silicon 1.25% Tungsten 9.5 9.0 to 10.0. chromium 16.5% nickel 32.5% 7 tungsten 9.5%

In the execution of this invention, several experimental steels were melted and fabricated. Melting was carried and the balance of said steel being essentially iron.

3 4 3. A high density, nonmagnetic steel of approximately tungsten 9.9% 8.4 grams/cm. and consisting essentially of: nitrogen 0.017%

carbon 0.09% and the balance of said steel being essentially iron. manganese 1.7% I silicon 1.55% 5 References Cited in the file of this patent Cilromium 161% UNITED STATES PATENTS mcket 33; 1,528,478 Hadfield Mar. 3, 1925 f 3 1,542,233 Girin June 16, 1925 10 1,953,229 Heron Apr. 3, 1934 and the balance of said steel being essentially iron. 1,991,433 w rman Feb. 19, 1935 2,587,613 Payson Mar. 4, 1952 4. A high density, nonmagnetic steel of approximately OTHER REFERENCES 8.4 am /cm. and consistin essentiall of:

gr 8 g y Evans: Wrought Heat Resisting Alloys for Gas Turbine carbon 0.05% 15 Service, Reprint N0. 31, reprinted from November 1945 manganese 17% issue of Metal Progress, page 4.

silicon 1.49% Gregg: Alloys of Iron and Tungsten, published for the chromium 164% Engineering Foundation by the McGraw-Hill Book Co.,

nickel 32.3% Inc., New York and London, 1934, pages 401 to 404. 

1. A HIGH DENSITY, NONMAGNETIC STEEL, OF APPROXIMATELY 8.4 GRAMS/CM.3 AND CONSISTING ESSENTIALLY OF: 